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osteoporosis

osteoporosis

introduction

  • in Australia, lifetime risk of osteoporosis in those over 50yrs age is 42% for women and 27% for men.
  • affects 2 million Australians
  • 20,000 hip fractures per year in Australia - increasing by 40% each decade
    • about 25% die within 12 months
    • 15-25% require long term care

risk factors

factors that allow rebate for DEXA scanning

  • prolonged corticosteroids Rx such as doses of oral prednisolone greater than 7.5mg per day for 3 months or more.
  • conditions with excess corticosteroids secretion
  • male hypogonadism
  • Turner syndrome
  • amenorrhoea lasting > 6 months before the age of 45 years
  • primary hyperparathyroidism
  • chronic liver disease
  • chronic renal disease
  • proven malabsorption disorders
  • rheumatoid disorders
  • conditions associated with thyroxine excess

other risk factors

diagnosis

Dual energy Xray Absorptiometry Scan (DEXA scan)

  • used to confirm Dx of osteoporosis and estimates severity of bone loss
  • can be used to determine response to Rx
  • lower radiation dose compared to other methods
  • results are given a T scores which are statistical scores relating to population standard deviations of 20 yr olds:
    • T score > -1.0 SD = normal
    • T score between -1.0 and -2.5 SD = osteopaenia
    • T score less than or equal to -2.5 SD = osteoporosis
    • T score less than or equal to -2.5 SD with 1 or more fragility fractures = severe osteoporosis

investigations of the cause

  • low calcium intake
  • vitamin D deficiency
  • oestrogen deficiency states
  • 5% of Caucasian adults with osteoporosis will have coeliac disease as the cause
  • in men, test for presence of hypogonadism and if present Rx with testosterone when necessary

treatment and prevention

calcium intake and supplementation

vitamin D supplementation for deficiency states

bisphosphonates

  • bisphosphonates can reduce progression of osteoporosis by inhibiting the resorption of bone
  • regarded as 1st line Rx used in conjunction with calcium and vitamin D supplementation.
  • C/I include oesophageal diseases

raloxifene

  • may be useful, particularly in women < 60yrs age (esp. in those concerned of breast cancer risk with hrt) or where bisphosphonates can't be used.
  • has similar risk of DVT as for HRT but does not relieve symptoms of menopause
  • only subsidised for post-menopausal women with PH osteoporotic fracture
  • C/I in men, premenopausal women, pregnancy and those with PH DVT

calcitriol

  • active form of vitamin D can be used as a 3rd line Rx for osteoporosis although evidence for its efficacy is less robust and it requires adequate calcium intake and risks hypercalcaemia, thus requires monitoring of serum calcium levels.
  • only subsidised for post-menopausal women with PH osteoporotic fracture

parathyroid hormone analogues

  • Although parathyroid hormone (PTH) increases the release of calcium from bone, intermittent use stimulates osteoblasts more than osteoclasts. By mimicking this effect of parathyroid hormone, teriparatide, an amino acid sequence similar to parathyroid hormone (PTH) aims to stimulate bone formation in patients with osteoporosis.
  • listed on PBS in 2009 for Rx of severe established osteoporosis (BMD T-score of -3.0 or less) in those at very high risk of fracture, who develop symptomatic fracture(s) despite at least 12 months of continuous antiresorptive Rx. Requires initialisation by a specialist (Auth. req.)
  • Rx duration limited to 18 months as risk of osteosarcoma, and thus Rx requires informed consent.
  • daily sc injection

oestrogen replacement therapy (HRT or ERT)

  • may be considered for postmenopausal women who are considered at low risk for cardiovascular disease or breast cancer

osteoclast inhibitors

  • denosumab
    • humanised monoclonal antibody which binds RANKL blocking the interaction with its receptor on the surface of osteoclasts which then inhibits development and activity of osteoclasts, leading to decreased bone resorption and increased bone density
    • studies suggest it reduced vertebral fractures, #NOF by around 50% compared with placebo incidence, but appears to cause more eczema, cellulitis, flatulence and perhaps a risk of immunocompromise with mildly higher rates of infections and malignancies
    • introduced in Aust in 2010, long acting s/c injuection

Bone Densitometry Unit

  • Level 4 - Western Centre For Health Research and Education Sunshine Hospital
  • To make a booking please fax your referrals to 03 8395 8258 or call 03 8395 8246/8119.
  • The unit is open for scanning on Tuesday and Wednesday between 9:00am-5:00pm.

Other references

osteoporosis.txt · Last modified: 2017/12/23 15:58 (external edit)